1. Field of Invention
The present invention is related to a security method for the verification of an Information Retrieval Request, a computer program product being stored in a computer-readable medium to carry out such a security method, a Security Device for the verification of an Information Retrieval Request as well as a Mobile Communication Network comprising such a Security Device.
2. Background Art
It is state of the art that different kinds of protocols are used for communication in a complex Mobile Communication Network. For example, in a Mobile Communication Network different kinds of servers are located. The different kinds of servers can be separated by their use and location. For example, a so-called Visited Location Register Server (VLR) can be used to coordinate several network cells and the respective network antennas and to store information from subscribers that are located in the VLR. Moreover, a so-called Home Location Register Server (HLR) can be used to store general or basic information for the network and in particular with respect to the users of the network, the so-called network subscribers and to store the present address of the VLR and the MSC of the subscriber that is logged in to the Mobile Communication Network. In commonly known Mobile Communication Networks, information about the mobile subscribers has to be passed between the different servers, in particular in circuit switched networks between the VLR and the HLR, or in the case of packet switched networks, between the Serving CPRS Support Node (SGSN) and the HLR. Sometimes the VLR is integrated or stored in the Mobile Switching Center (MSC) and therefore subscriber information is stored in the MSC/VLR or in the Mobile Switching Center Server (MSCS) and therefore in the so-called MSCS/VLR. The SGSN is at the same hierarchical level in the General Packet Radio Service (GPRS) core network as a MSC in a circuit switched core network, e.g. a GSM network. The SGSN contains a register that is called SGSN Location register (SLR), which stores subscriber information similar to the information stored in the VLR in the MSC, i.e. the MSC/VLR pair is comparable to the SGSN/SLR pair. In the following specification an Information Retrieval Request may be directed to any of such kinds of Location Registers. Such a Location Register may be, for example, the VLR, the MSC/VLR, the MSCS/VLR, the SGSN or the SGSN/SLR or any similar equipment in a Mobile Communication Network. The Information Retrieval Request may be performed to retrieve certain subscriber information from the Location Register respectively Location Register Server. Such information can, for example, be basic information stored in the HLR and passed to the Location Register, e.g. the VLR or the SGSN. This leads to a communication in a first direction. The other way round, data which is stored on the Location Register, e.g. the VLR or the SGSN, can also be transmitted to the HLR, for example, to give the HLR notice where the different mobile subscribers are located in the respective cell or in the respective area coordinated by the respective VLR or SGSN. The data stored in the Location Register, e.g. the VLR or the SGSN can, for example, comprise information about the location, the usage or the movement of the mobile subscriber.
It has occurred that by the increase of technical possibilities in the network industry, a security problem can arise with commonly known structures of Mobile Communication Networks. For example, the risk exists that retrieval of data is requested by an outside server which is not an authorized HLR. This means, retrieval of data can be requested, for example, from a frauded HLR which is not part of the Mobile Communication Network that is operated by the Mobile Network Operator to which a certain user is registered or from a frauded HLR which is not located in the same country as a certain user is registered to a Mobile Network Operator. Therefore, in commonly known Mobile Communication Networks such an outside Sending Entity can label itself as a fraud or fake HLR and therefore tries to request secured information located on the respective Location Register, e.g. VLR or SGSN.